1. Field of the Invention
This invention directs itself to a disposable protective cover for use with a Goldmann-type applanation tonometer, as well as a kit type package for providing the cover. In particular, this invention directs itself to a disposable cover which may in general be described as a condom like cover member having an overall bag contour or in order to interface in a more contiguous manner may be pre-formed into a frusto-conical contour, formed from an optically transparent material which is sufficiently thin so as not to interfere with the tonometer measurement. More in particular, this invention pertains to a disposable protective cover having at least one tab member for use in handling the cover during application to and removal from the tonometer head. Further, this invention directs itself to a kit for providing a sterile tonometer cover which is formed in one wall of the package.
2. Prior Art
Disposable tonometers, and disposable tonometer covers, are well-known in the art. The best prior art known to the Applicants include U.S. Pat. Nos. 1,743,461; 2,780,221; 2,984,099; 3,049,001; 3,272,001; 3,282,090; 3,330,152; 3,338,090; 3,376,735; 3,443,421; 3,511,085; 3,714,819; 4,213,464; and, 4,593,699.
Some prior art systems, like that shown in U.S. Pat. No. 4,213,464 are directed to tonometer transducer assemblies which have provisions for a removable and interchangeable membrane seal. Such membrane seals are formed from resilient material, but must be retained to the conical surface of the transducer by an O-ring which fits in an annular groove formed in the surface of the transducer. However, the annular groove does not exist in the current Goldmann-type applanation tonometers in use today, therefore, the tonometer heads would require modification or replacement for use of this type prior art system. In contradistinction, the present invention is retrofittable in existing Goldmann-type tonometer heads without modification thereto.
In other prior art systems, such as U.S. Pat. Nos. 3,049,001, and 3,272,001, there are provided tonometer systems having protective sheaths placed over the end of the tonometer. Although these sheaths may provide a sterile contact for the instrument on the cornea of the eye, they are used on tonometer heads which include a cylindrical portion to which the sheath can frictionally retain itself. In addition, these prior art systems are not used in conjunction with optical instruments and therefore do not require the sheath to be formed from an optically transparent material, whose compositions typically do not exhibit the elasticity required to form a sheath which is frictionally self-retaining, as required by the systems in the prior art. Therefore, substitution of materials alone would not render the prior art system devices usable with the Goldmann-type applanation tonometer. In still other prior art devices, such as U.S. Pat. No. 3,338,090, make use of a replaceable tip for an applanation tonometer which is optically transparent. However, such tips are held to the applanation head by either a magnetized collar or a spring clip arrangement. Obviously, these replaceable tips as disclosed in the prior art are far more costly and complex than the condom like tip member or preformed membrane-like cover of the subject invention. Additionally, the covers as disclosed in the prior art are not adaptable for retention on the conical surface of the currently used Goldmann-type applanation tonometer. Further, the covers of the prior art do not provide for a means of handling the cover during application to the tonometer head and removal therefrom, as provided by the subject invention.